Ignition devices for internal combustion engines of vehicles are recently required to have a higher suitability in installing on a vehicle and a higher reliability in electrical connection between parts.
The present invention is to provide, in response to the above-mentioned requirements, an ignition device of a single unit having an ignition distributor and an ignition coil. The invention aims, in combining an ignition coil, to prevent the ignition device from malfunctioning by preventing the leakage flux of the ignition coil from being an undesirable influence on a magnetism-sensitive rotation signal generating means (for instance, an electromagnetic pickup using a permanent magnet and a coil) which is built in the ignition distributor.
As will be described hereinlater, when an ignition coil is incorporated in a single unit of a distributor assembly, the leakage flux from the ignition coil is apt to affect rotation signal generating means, such as an electromagnetic pick up, which is arranged to produce a triggering signal by detecting the rotation of the engine crakshaft where the triggering signal will be used to control the energization of the primary winding of the ignition coil. Namely, when the rotation signal generating means is of an electromagnetic type, a noise voltage may be induced due to the leakage flux from the ignition coil resulting in false triggering of the ignition coil. As a result, the ignition system malfunctions, and thus proper ignition timing is deteriorated.